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Great big stores cost a fortune to heat and leave a huge carbon footprint, so both economic and environmental self-interest argues for innovation. Walmart has put windmills in a few of its parking lots; Target has plants on some of its roofs to harvest rainwater and cool the stores in summer. Now Ikea, the world's favorite Swedish home furnisher, is trying to give America a gentle shove into using renewable resources. It is working with the U.S. Department of Energy's National Renewable Energy Laboratory to use underground heat to manage temperatures inside its new 415,000-sq.-ft. (38,550 sq m) retail store near Denver, scheduled to open next year. (See TIME's special report on the environment.)

Geothermal heat pumps take advantage of the fact that while the earth's surface temperatures can sizzle in summer and plunge in winter, underground things stay nice and moderate  generally 45°F to 75°F (2°C to 24°C). In Colorado, Ikea will drill 130 holes to a depth of 500 ft. (150 m) beneath the building's parking garage and install pipes that send liquid down to capture that perfect temperature and run it back up to a heat pump. The pump can then cool in-store air or heat it, depending on the season. According to the U.S. Environmental Protection Agency, systems using geothermal heat pumps, sometimes called GeoExchange or ground-source pumps, can reduce energy consumption and emissions by up to 72% compared with electric resistance heating and standard air-conditioning. (See a brief history of air-conditioning.)

Shoppers looking to try this technology at home will find that the front-end costs for geothermal systems are high  about $7,500 for a typical residence  but once built, they are relatively cheap to run. Systems can be installed in a few days beneath the lawn or driveway or under a new or existing house. Several states offer tax incentives for installation, and the International Ground Source Heat Pump Association estimates that some customers recoup their investment in as little as three years.

Although demand for geothermal heat pumps in recent years has been increasing 10% to 13% annually in the U.S., Ikea's clean-chic ethos could give this worthy (but not particularly sexy) technology a bump into the mainstream.

The company takes its environmental responsibility seriously: after all, at any given moment, its flat-packed sofas and recycled-plastic wastebaskets are on the high seas, guzzling fuel to get to living rooms from Tokyo to Riyadh. Ikea already uses geothermal heat-pump systems in other countries, and it's considering making the system's plans public to encourage other retailers in the U.S. and elsewhere to think about doing the same. If these plans are easier to follow than the manuals for Ikea's build-it-yourself furniture, the golden age of geothermal may soon be upon us.